All data taken into account in the accumulation is shown in the graph ‘interpolated raw data’ (top left button above the graph).

The red graph shows the accumulation of 0,114 μGy/h
based on an estimated average for Japan of 1000 μGy per year (equates 0,114 μGy/h *24 hours * 365 days). The accumulation starts with the first available value of the data set after 13.3.2011 (see missing values above).

The green graph shows the accumulation of Vmax.
The accumulation starts with the first available value of the data set after 13.3.2011 (see missing values above).

Colour scale:

< Vmax

< 10 * Vmax

< 100 * Vmax

> 100 * Vmax

The colour scale is based on the maximum Value (Vmax) measured at the location of the Geiger counter prior to the accident. Therefore allowing to spell out the changes in comparison to the values prior to the accident.

Natural radiation:

Total annual natural radiation dose for people living in Japan is estimated to be about 1000 microsieverts
[RERF's Messages]

All living organisms are continually exposed to ionizing radiation,which has always existed naturally. The
sources of that exposure are cosmic rays that come from
outer space and from the surface of the Sun, terrestrial
radionuclides that occur in the Earth’s crust, in building
materials and in air, water and foods and in the human
body itself. For more information see

The unit gray, [Gy], measures radiation which is absorbed into any
material.

Equivalent dose [Sv]:

The unit sievert, [Sv], specifically measures radiation
which is absorbed by a person.
The equivalent dose to a person is found by
multiplying the absorbed dose, in gray, by a radiation weighting factor (WR).
The radiation weighting factor WR is introduced to allow for the different relative biological effects of
different types of ionizing radiation on human tissue.

In terms of SI base units:

1 Sv = 1 Gy ⋅ WR

where Sv=sievert, Gy=gray, WR=weighting factor specific
to each type of radiation and tissue.

Radiation weighting factor (WR):

For x-rays and gamma rays and electrons absorbed by human tissue, WR is 1.
For alpha particles it is 20. To compute Sieverts from Grays, simply
multiply by WR. This is obviously a simplification. The radiation weighting
factor WRapproximates what otherwise would be very complicated
computations. The values for WR change periodically as new research refines
the approximations [1].

Effective dose [Sv]:

The probability of a harmful effect from radiation exposure depends on what part or parts of the body are exposed. Some organs are more sensitive to radiation than others.
A tissue weighting factor is used to take this into account. When an equivalent dose to an organ is multiplied by the tissue weighting factor for that organ the result is the
effective dose to that organ. If more than one organ is exposed then the effective dose, is the sum of the effective doses to all exposed organs [1].